1. Field of the Invention
The present invention relates to a positioning structure of a clamping device of a disc carrier assembly for an optical disc drive. In particular, the present invention relates to a positioning structure of a clamping device of a disc carrier assembly for an optical disc drive that prevents inadvertent disengagement of the clamping device.
2. Description of Related Art
FIGS. 1 and 2 of the drawings illustrate an optical disc drive with a conventional disc carrier. The optical disc drive comprises a spindle motor including a disc carrier 10, a clamping device 20, a shaft 30, a stator assembly 40, a bearing seat 50, and a base 60. The disc carrier 10 is a rotor of the spindle motor and includes an engaging portion 11 that has an axial tube 111 with an axial hole 112. The clamping device 20 includes a central hole 21, plural clamping members 22, and plural elastic elements 23.
An outer periphery of the shaft 30 is tightly fitted to an inner periphery of the axial hole 112 of the axial tube 111, and the inner periphery of the central hole 21 of the clamping device 20 is tightly fitted around an outer periphery of the axial tube 111. The disc carrier 10 and the clamping device 20 are coupled by the shaft 30 to the stator assembly 40, the bearing seat 50, and the base 60 to thereby form a spindle motor for an optical disc drive. An optical disc can be releasably clamped by the clamping members 22 of the clamping device 20, and the data stored in the optical disc can be read through stable rotation of the disc carrier.
Although the tight fitting between the disc carrier 10 and the clamping device 20 simplifies and shortens the assembling procedure of the spindle motor, the clamping device 20 that is usually made of plastic provides a relatively low tolerance to deformation when compared with metal. In particular, the inner periphery of the central hole 21 of the plastic clamping device 20 fails to provide a sufficient engaging force after engagement with the outer periphery of the axial tube 111 of the metal engaging portion 11. Due to insufficient engaging force and unstable assembly between the inner periphery of the central hole 21 of the plastic clamping device 20 and the outer periphery of the metal axial tube 111, the clamping device 20 might be undesirably disengaged from the axial tube 111 of the carrier disc 10 while removing the optical disc from the clamping members 22 of the clamping device 20.